AUGUSTA, Ga. — In the toughest opening round at the Masters in 10 years, it all felt so easy to Charley Hoffman.

For the better part of three hours, in a ferocious wind that made the Georgia pines creak, he had the right yardage for the perfect club to hit every shot he wanted. And then he made the putts, so many that it felt as though he never missed.

Hoffman, the defending Valero Texas Open champion, made seven birdies over his last 11 holes for a 7-under 65.

It was 10 shots better than the average score Thursday at Augusta National. His four-shot lead was the largest for the opening round at the Masters in 62 years.

It was even more surreal for Dustin Johnson. He didn’t even get to play.

Johnson, No. 1 in the world and playing the best golf of his life, was a few minutes away from his tee time when his head overruled his heart. He left the practice green and took a sharp turn away from the first tee toward the clubhouse to withdraw because of a freak injury to his back.

“My heart is in it and wants to play,” he said. “The more I thought about it, I just wasn’t going to have a chance.”

Johnson was still trying to digest the last 24 hours, as shocking as any for a No. 1 player going into a major. He was in his rental home Wednesday when he went to move his car in a downpour. Wearing only socks, he slipped on the hardwood steps and crashed onto his left elbow and lower back, calling for his brother to help him.

Even as he tried to warm up on Thursday, he slowly shook his head because of the pain he felt when he struck the ball.

With gusts approaching 40 mph, Hoffman and Masters newcomer William McGirt (69) were the only players to break 70.

Hoffman didn’t have reason to believe he would be one of them. He three-putted his third hole for bogey. He three-putted the fifth hole for bogey, both putts affected by the wind.

“After that, I can’t remember missing a putt,” Hoffman said.

His four-shot lead was the largest at the Masters for the opening round since Jack Burke Jr. had a four-shot lead in 1955.

Lee Westwood, who has the credentials as the best player to have never won a major, ran off five straight birdies late in the afternoon and salvaged a 70. Only eight other players broke par, a group that included Phil Mickelson, Justin Rose and Sergio Garcia.

Rory McIlroy, needing only a green jacket to complete the career Grand Slam, used a nifty short game to stay in the mix. He saved two tough pars after missing the green in the wrong spots on Nos. 10 and 11, ran off three birdies in the middle of the back nine, and closed with another par save for a 72.

The wind was so strong that it blew golf balls some 6 feet on the greens as Adam Scott and defending champion Danny Willett were getting ready to putt.

The par-5 15th hole, historically the easiest at Augusta National, was the ninth hardest because of strong gusts and a back pin. No need to explain that to Jordan Spieth. One of the former University of Texas star’s shot spun back into the water. Another shot went well over the green. He made a quadruple-bogey 9 and shot 75.

Boerne’s Jimmy Walker shot a 4-over 76, tied for 54th.

Two-time Masters champion Bubba Watson joked that Hoffman was playing the members’ tee. The average score was 74.98, the highest for an opening round since 2007. Mickelson finished his 71 and said that anything at par or better would be a “phenomenal score.”